Saudi Journal of Kidney Diseases and Transplantation

: 2017  |  Volume : 28  |  Issue : 2  |  Page : 330--335

Associated anomalies and clinical outcome in children with ectopic kidney

Cagla Serpil Dogan1, Mustafa Erman Dorterler2, Mustafa Devran Aybar3, Halil Ciftci4, Mehmet Gulum4, Yigit Akin4, Ercan Yeni4,  
1 Division of Pediatric Nephrology, Sanliurfa Children's Hospital, Sanliurfa, Turkey
2 Department of Pediatric Surgery, University of Harran, Sanliurfa, Turkey
3 Department of Radiology, Sanliurfa Children's Hospital, Sanliurfa, Turkey
4 Department of Urology, University of Harran, Sanliurfa, Turkey

Correspondence Address:
Cagla Serpil Dogan
Division of Pediatric Nephrology, Antalya Training and Research Hospital, 07059 Antalya


Urological anomalies can be seen in children with renal ectopia (RE) and can result in renal impairment. Therefore, we evaluated associated anomalies and renal outcome in our patients with RE. Sixty-eight children who were diagnosed with RE between January 2009–May 2014 were retrospectively studied. A total of 68 patients, 36 (52.9%) boys, with a median age of 67 months (4–201) and a median follow-up period of 14 months (3–113) were included in the study. Simple RE (S-RE) was found in 51 (75%) patients, of which 46 were unilateral and five were bilateral (discoid kidney). Crossed RE (C-RE) was detected in 17 (25%) patients. Voiding cystourethrogram was performed in 21/51 (41.2%) patients in S-RE group and 5/17 (29.4%) in C-RE group. We did not find vesicoureteral reflux (VUR) in any of the patients with C-RE, whereas, in S-RE group, VUR was demonstrated in six (6/21 - 28.6%) patients. Pelviureteric junction obstruction in ectopic kidney was found in two patients with S-RE and one with C-RE. Two patients (2/17 - 11.7%) had neurogenic bladder due to meningomyelocele, accompanied by imperforate anus in C-RE group. There were no significant differences in other associated urological anomalies between two groups. Renal impairment developed mostly in patients with additional urinary anomaly. The children with RE may have associated urinary anomalies, of which VUR is the most common. Complete urological investigation and regular follow-up are required in selected cases.

How to cite this article:
Dogan CS, Dorterler ME, Aybar MD, Ciftci H, Gulum M, Akin Y, Yeni E. Associated anomalies and clinical outcome in children with ectopic kidney.Saudi J Kidney Dis Transpl 2017;28:330-335

How to cite this URL:
Dogan CS, Dorterler ME, Aybar MD, Ciftci H, Gulum M, Akin Y, Yeni E. Associated anomalies and clinical outcome in children with ectopic kidney. Saudi J Kidney Dis Transpl [serial online] 2017 [cited 2021 Jan 18 ];28:330-335
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Full Text


Kidneys begin to develop at four-week gestation by the union of the ureteric bud with the metanephric blastema at the level of the first or second sacral segment and gradually ascend to the renal fossa during embryogenesis.[1] Renal ectopia (RE) implies that the kidney lies outside the renal fossa.[2]

Simple RE (S-RE) is an ipsilateral developmental anomaly resulting from failing to ascend out of the pelvic cavity. S-RE can be unilateral or bilateral and can be found anywhere along the normal embryologic ascend of the kidney, mostly in the pelvis.[2],[3] In bilateral pelvic S-RE, the kidneys often fuse into a midline mass of renal tissue, which is referred to as discoid kidney.

Crossed RE (C-RE) is a rare congenital malformation, in which both kidneys are located unilaterally. The crossed kidney is situated on the contralateral side of its ureteric orifice. Ninety percent of crossed ectopic kidneys are fused, and the crossed kidney usually lies below the orthotopic kidney and fuses together at its lower pole. This anomaly is thought to result from abnormal development of the ureteric bud and metanephric blastema. Teratogenic and genetic factors, pressure from abnormally placed umbilical arteries, and malrotation of the caudal end of the fetus have also been speculated to play a role in the etiology of cross fused RE.[3],[4] Crossed ectopia without fusion is an uncommon variety of C-RE, with an incidence of 1 in 75,000 autopsies.[5]

Most cases of RE are asymptomatic during life and diagnosed only incidentally. However, patients may present with signs and symptoms of urinary tract obstruction, infection or calculi due to the abnormal position of the kidney, and/ or the abnormal course of the ureters. Vesicoureteral reflux (VUR) is also commonly associated with ectopic or orthotopic kidney.[3],[4],[6],[7]

The aim of the present study is to evaluate associated urological abnormalities, nonurological associations, and renal outcome in children with RE.

 Materials and Methods

We retrospectively reviewed the medical records of 82 children with ectopic kidney who were followed in two different hospitals in Sanliurfa (Sanliurfa Children’s Hospital, Division of Pediatric Nephrology and Harran University, Department of Urology and Pediatric Surgery) between January 2009 and May 2014. In eight cases, 99mtechnetium dimmercaptosuccinic acid (DMSA) scintigraphy was not available, and six cases were lost to follow-up. These patients were excluded from the study. In the remaining 68 cases, the diagnosis of ectopic kidney was based on US findings and confirmed by DMSA. Differential renal function was calculated as the geometric mean of the anterior and posterior views on DMSA scan. Pelvic dilatation was diagnosed by US and graded according to the Society for Fetal Urology classification.[8] Indications for a voiding cystourethrogram (VCUG) included the presence of hydronephrosis, hydroureteronephrosis, or increased echogenicity of renal parenchyma of ectopic and/or orthotopic kidney on ultrasound (US) or renal scarring on DMSA scan. VUR was graded using the system of the International Reflux Study in Children.[9] Estimated glomerular filtration rate (eGFR) was calculated using the Schwartz formula,[10] and chronic kidney impairment was classified according to the Kidney Disease Outcomes Quality Initiative Guidelines.[11] In children younger than one year of age, age specific serum creatinine values were used to assess renal function. Hypertension was defined as average systolic and/or diastolic blood pressure (≥95th percentile for sex, age, and height on at least three separate occasions or as the use of antihypertensive drugs.[12] If a random dipstick urinalysis was positive for protein (1+ or more) protein/creatinine ratio in early morning urine was estimated and, values greater than 0.2 mg/mg was considered as proteinuria. Hyperfiltration was defined as eGFR >130 mL/min/1.73/m2.[13] Tc-99m-diethylene-triamine pentaacetate (DTPA) diuretic radionuclide scan was used to evaluate the patients with suspected upper urinary tract obstruction.

 Statistical Analyses

All statistical analyses were performed using Statistical Package for the Social Sciences (SPSS) software for Windows 16.0 (SPSS Inc., Chicago, IL, USA), and the results are expressed as percentage, mean ± standard deviation, and median (range) as appropriate. Categorical parameters were compared using Chi-square or Fisher’s exact test. For comparison of continuous variables, Mann–Whitney U-test was performed. P <0.05 was considered statistically significant.


A total of 68 patients, 36 (52.9%) boys, were included in the study. Median age was 67 (range 4–201) months and median follow-up duration was 14 (range; 3–113) months. A total of 47 (69.1 %) patients were followed for ≥1 year. In 8 (11.7 %) patients, the diagnosis was made antenatally. Median age at postnatal diagnosis of remaining sixty children was 48 (range; 1–187) months. In seven (10.3 %) patients, ectopic kidney was detected incidentally on US. Five patients with cardiac anomalies, two with anorectal malformations + meningomyelocele, and one with Turner syndrome were diagnosed by abdominal US routinely performed to detect possible urinary anomalies (8/68–11.7%). Six (8.8%) patients were referred to our hospital with suspected renal agenesis on US examination. In six (8.8%) patients, initial symptoms could not be detected in their medical records. In the rest of the patients, a US was performed due to abdominal pain in 23 (33.8%) patients, enuresis in seven (10.3 %), symptoms of urinary tract infection (UTI) in three (4.4%).

Simple RE and C-RE were found in 51 (75%) and 17 (25%) patients, respectively. Demographic and clinical characteristics of patients are given in [Table 1].{Table 1}

Simple renal ectopia

Unilateral S-RE was found in 46 patients (pelvic in 41 patients and lumbar in 5). Five patients had bilateral ectopic fused kidney (discoid kidney).

Urological anomalies

A VCUG was performed in 21/51 (41.2%) patients. VUR was discovered in six (6/21 -28.6%) patients; Grade II, III, and V reflux in ectopic kidney in three patients, Grade III and IV reflux in orthotopic kidney in two patients, and bilateral Grade IV VUR + bilateral incomplete duplicated collecting system in one. The last patient was lost to follow-up. In the other patients, ureteroneocystostomy in three patients and subureteric injection in one patient were performed. The patient with Grade II VUR was followed without surgical intervention. DMSA scan showed renal scarring in all patients with Grade III, IV, and V VUR.

Except for one, all patients with VUR were male.

Pelviureteric junction obstruction (PUJO) in ectopic kidney was demonstrated in two (3.9%) patients.

In two patients, solitary ectopic kidney on the right side was discovered, one of whom, as above-mentioned, had also Grade V reflux.

Estimated GFR was calculated in 26/51 patients, with a median eGFR of 111.5 mL/min/ 1.73 m2 (range: 67–170). Kidney function was reduced in patients with solitary ectopic kidney + Grade V VUR and bilateral Grade IV VUR + bilateral in complete duplicated collecting system. One more patient with increased renal parenchymal echogenicity and loss of corticomedullary differentiation in both kidneys on US had reduced GFR. In this patient, DMSA scan demonstrated hypofunctioning ectopic right kidney (differential function; 30 %), VUR was not determined.

One patient had eGFR >160 mL/min/1.73m2 but without proteinuria. None of the patients developed proteinuria or hypertension during the study period.

Mean differential renal function of 46 patients with unilateral ectopic kidney was significantly lower than the orthotopic one; 37.3% ± 9.9% (range; 7%–48%) and 62.6% ± 9.9% (range; 52%–93%), respectively (P = 0.001).

In four patients with bilateral ectopic fused kidneys, differential renal function could not be calculated. In the remaining one patient, differential function was 50% for each kidney. Nonurological anomalies were found in six (11.7%) patients (cardiac anomalies in three patients and albinism, bowel malrotation, and Turner syndrome in one patient each).

Crossed renal ectopia

In our study group, all patients (n = 17) had crossed RE with fusion. In all cases, the ectopic kidney was located below the normal one.

Urological and nonurological anomalies

In two patients, neurogenic bladder due to meningomyelocele, and imperforate anus were associated with crossed ectopic kidney. One of whom had ectopic left kidney with Grade III hydronephrosis and DTPA with furosemide test documented PUJO. In this patient, PUJO was followed closely without surgical intervention. In one case, right-sided multicystic dysplastic kidney (MCDK) and crossed fused ectopic left kidney were detected. A VCUG was performed in 5/17 (29.4%) patients. We could not demonstrate a VUR in any of our patients. eGFR was calculated in 10/17 patients, with a median eGFR of 110 mL/min/1.73 m2 (range: 96–130). DMSA showed nonfunctioning right kidney in the patient who had orthotopic right-sided MCDK. In six patients, differential renal function could not be calculated due to superimposition of the fused kidney. In the rest of patients (10/17), mean differential renal function was determined as 40.7% ± 15.4% (range: 15–50) and 62.1% ± 12.2% (range; 50–85) in ectopic and orthotopic kidney, respectively (P = 0.001). No patients developed proteinuria, hypertension, or chronic renal insufficiency during the study period.

We determined a cardiac anomaly in two patients and inguinal hernia in one.

There were no significant differences in associated urological (VUR and PUJO) and nonurological anomalies between S-RE and C-RE patients (P = 0.5 and P = 0.6, respectively).


In this study, we retrospectively evaluated the frequency of associated urological/nonurological anomalies, renal outcome, and clinical characteristics of the patients with RE.

Although the rate of VUR in patients with RE varies from 2% to 58% in various series,[2],[3],[14],[15],[16],[17] in most studies, it is reported at around 20%.[3] Similarly, in our study, when VCUG was performed in 41% of patients in S-RE group, VUR was determined in 28.6% patients. In C-RE group, in which five out of 17 children underwent VCUG, we did not detect VUR. Although previous studies have reported that VUR to orthotopic kidney was significantly more frequent that of ectopic kidney,[2],[3],[7] in the present study, the frequency of VUR in both kidneys did not statistically differ. Similarly, we did not observe any statistical difference in the frequency of obstructive uropathies between S-RE and C-RE.

Ectopic kidneys may also be associated with other congenital anomalies such as urogenital, gastrointestinal, cardiovascular, and skeletal disorders. In our study, nonurological anomalies were found in 11.7% and 29.4% of the patients with S-RE and C-RE, respectively, but the difference was not statistically significant between two groups. In C-RE group, we observed that two patients (2/17 - 11.7%) had neurogenic bladder due to meningomyelocele, accompanied by imperforate anus. Similarly, Arena et al[2] reported that two of 24 patients with C-RE had imperforate anus with sacral agenesis. Solanki et al[5] demonstrated the association between C-RE and anorectal malformations in two of six patients. Polak-Jonkisz et al[4] detected neurogenic bladder due to meningomyelocele, coexisting with imperforate anus as in our cases, in two of five patients with C-RE. We think that these findings may point out to a possible relationship between anorectal malformations, anomalies of the lumbo-sacral column, and C-RE.

The studies evaluating hypertension and proteinuria, as markers of renal injury, in pediatric patients with RE are limited. van den Bosch et al[3] detected urine protein-to-creatinine ratio >20 mg/mmol and urine albumin-to-creatinine ratio >4 mg/mmol in 32% and 12% of the patients, respectively, with a median age of 7.7 years. In that study, Schwartz GFR was <90 mL/min/1.73 m2 in 22% of the patients, hypertension developed in two patients with VUR to orthotopic kidney in S-RE group, and there was no statistical difference in parameters of renal function between the patients with S-RE and C-RE. In our study, we determined that eGFR was <90 mL/min/1.73 m2 in 3 out of 51 (5.8%) patients in S-RE group, in those with additional urological anomaly. Protein excretion was evaluated by dipstick in most patients. Hypertension and/or proteinuria were not found in any of our patients, with a median age of 5.6 years.

Consistent with prior reports, we found that ectopic kidney was significantly more hypofunctioning compared to orthotopic one.[2],[3],[7],[16] However, ectopic kidney did not affect global renal function if there was no additional urological anomaly.

In the present study, the interval from the date of diagnosis until the last visit was accepted as the period of follow-up. Although our cohort had short follow-up period (median; 1.1 years), the median age of all patients at last visit was relatively high (median: 5.6 years).

Our study has several limitations. First, there were inadequate or missing data due to short follow-up period and retrospective design of the study. Second, proteinuria could not be evaluated with more sensitive methods such as albumin excretion.

In conclusion, urinary tract abnormalities coexisting with RE, such as VUR or obstructive uropathies, may increase the risk of renal failure. To decrease the risk of renal impairment, imaging studies such as VCUG, CT scan, and radionuclide scan should be done in individual cases where further urologic investigations are necessary. The incidence of associated urological and nonurological anomalies between S-RE and C-RE is not statistically significant. However, crossed fused ectopic kidneys may be more often associated with anorectal malformations.

Conflict of interest:

None declared.


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